Torsion damping mechanism

ABSTRACT

A mechanism (19) disposed in a torque converter housing (24) for damping torsionals in a vehicle driveline. The mechanism comprises a viscous coupling (22) including a housing (64) having two sidewalls (24a, 68) defining a chamber (70) containing a viscous liquid, and a clutch member (72) disposed in the chamber for viscous clutching coaction with the housing. One of the sidewalls (24a) is defined by an end wall of the torque converter housing. The housing and clutch member are interconnected by a spring assembly (20) including flat torsion springs (61, 62) which transmit steady-state driveline torque and isolate driveline torsionals. The inner surfaces (24b, 68a) of the housing each include two circumferentially spaced clutching surfaces separated by the clutch member. The clutch member has oppositely facing surfaces (72b, 72c) each which include two flat circumferentially spaced clutching surfaces. When the clutching surfaces of the housing are disposed opposite the clutching surfaces of the clutch member, the clutching coaction therebetween is a maximum. When the clutching surfaces of the housing are disposed opposite the spaces between the clutching surfaces of the clutch member, the clutching coaction is a minimum.

This is a continuation, of application Ser. No. 615,017 filed May 29,1984 and now U.S. Pat. No. 4,576,259.

CROSS REFERENCE TO RELATION APPLICATIONS

This application is related to U.S. patent application Ser. No. 564,537,filed Dec. 22, 1983 and to U.S. patent application Ser. No. 615,012,filed May 29, 1984 now U.S. Pat. No. 4,557,357. Both applications areassigned to the assignee of this application.

BACKGROUND OF THE INVENTION

This invention relates to driveline torsion damping mechanisms operableover the entire operational range of a driveline. More specifically, theinvention relates to such mechanisms for vehicle drivelines.

It is well-known that the speed of an Otto or Diesel engine output orcrankshaft varies even during so-called steady-state operation of theengine, i.e., the shaft continuously accelerates and decelerates aboutthe average speed of the shaft. The accelerations and decelerations are,of course for the most part, a result of power pulses from enginecylinders. The pulses may be of uniform frequency and amplitude whencylinder charge density, air/fuel ratio, and ignition are uniform.However, such uniformity does not always occur, thereby producing pulseswhich vary substantially in frequency and amplitude. Whether uniform ornot, the pulses, which are herein referred to torsionals, aretransmitted through vehicle drivelines and to passengers in vehicles.The torsionals, which manifest themselves as vibrations, are detrimentalto drivelines and derogate passenger-ride quality. Further, when anengine is abruptly accelerated and/or decelerated by accelerator pedalmovement, torque pulses ring through the driveline and also derogateride quality, such pulses are herein also referred to as torsionals.

Since the inception of the automobile, many torsion damping devices orschemes have been proposed and used to isolate and dampen drivelinetorsionals. For example, master clutches, used in combination withmechanical transmissions, have long employed springs and secondarymechanical friction devices to respectively isolate and dampentorsionals. Typically, torsionals are isolated or absorbed by aplurality of circumferentially spaced, coil springs disposed in parallelbetween the master clutch primary friction input and splined output.Damping is provided by secondary mechanical friction surfaces disposedin parallel with the springs and biased together with a predeterminedforce. Damping occurs when the amplitude of the torsionals exceeds thebreakaway or slip torque of the secondary friction surfaces. With thisarrangement, portions of the torsionals less than the slip torque of thesecondary friction surfaces are transmitted directly through the clutchwithout flexing or isolation by the springs, i.e., the arrangementprovides neither torsion isolation nor damping. If the slip torque ofthe secondary friction surfaces is reduced by design or wear of thesecondary surfaces, damping is reduced. Further, any portions of thetorsionals greater than the spring energy absorption or storage capacityare also transmitted directly through the clutch. If the spring rate isincreased to provide greater storage capacity and prevent springcollapse, the springs transmit lesser amplitude torsionals directlythrough with little or no effective isolation or absorption of thetorsionals.

To increase the operational spring range and storage capacity of atorsion damping assembly, Wemp in U.S. Pat. No. 1,978,922, proposedusing a low spring rate torsion sleeve capable of flexing substantiallymore than the coil springs used with master clutches. This arrangement,like the master clutch arrangement, also employs secondary mechanicalfriction surfaces disposed in parallel and biased together with apredetermined force to provide damping. Hence, the Wemp arrangement alsofails to provide isolation and damping of torsionals below the slip orbreakaway torque of the secondary friction surfaces. The Wemparrangement is also underdamped if the slip or breakaway torque of thesecondary friction surfaces is reduced.

The advent of torque converter-type automatic transissions ushered in awhole new perception of torsion damping and, of course, passenger ridequality. While torque converters have many advantages, one beingtorsional damping, they embody inherent slip and, therefore, inherentlosses in vehicle fuel economy. In an effort to minimize this slippageand thereby optimize or improve fuel economy, various efforts have beenmade to bypass the torque converter with some manner of direct drivewhich is typically brought into play when a vehicle is operating in thehigher speed ratios of the transmission. While these direct-drive bypassarrangements have resulted in fuel economy improvement, they have alsobrought back driveline vibration with resultant derogation in thevehicle ride quality that passengers have become accustomed to over theyears. The direct drive bypasses, for the most part, have been in theform of master type friction clutches with torsion damping devicessimilar to the previously mentioned devices. One example of such abypass is disclosed in U.S. Pat. No. 4,194,604. Two further examples ofbypass drives are disclosed in U.S. Pat. Nos. 3,977,502 and 4,317,510.In the '502 patent, the master type clutch engagement force is such thatthe clutch primary friction surface continuously slips or slips inresponse to torsionals above a predetermined amount. This arrangement isdifficult to control since the engagement force must vary with drivelinetorque. In the '510 patent, the master clutch incorporates a viscouscoupling which continuously slips to dampen torsionals in a manneranalogous to the continously slipping clutch in the '502 patent. Withthe arrangement in both of these patents, substantially all of theenergy from the engine to the transmission must be transmitted acrossslipping surfaces; hence, both arrangements generate substantial amountsof heat and, of course, losses in the form of fuel economy. A thirdbypass arrangement, as disclosed in U.S. Pat. No. 4,138,003, includesthe master type clutch in combination with low-rate torsion isolationsprings which may be of the helical torsion type or of the torsion bartype analogous to the arrangement disclosed in previously mentioned U.S.Pat. No. 1,978,922. It is also known to use flat torsion springs invibration dampers, as diclosed in U.S. Pat. No. 4,181,208.

Previously mentioned copending U.S. application Ser. No. 564,537 andentitled Torsion Damping Assembly discloses the use of a viscouscoupling in lieu of the secondary mechanical friction surfaces used inthe prior art torsional damping mechanisms. Since the clutching mediumtherein is a viscous liquid, breakaway torque associated with themechanical friction surfaces is eliminated. Hence, the coupling providesdamping over the entire operational or torque range of the assembly. Thecoupling has a constant damping factor and has provided excellentresults in tested vehicles. The torsion damping mechanism disclosedherein improves the assembly of the copending application by varying thedamping factor of the viscous coupling therein.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a torsion dampingmechanism which is effective to isolate and dampen driveline torsionalsover substantially the entire operational range of the driveline.

Another object of the present invention is to provide such a mechanismwhich varies the damping factor of the mechanism as a function ofdriveline torque.

Another object of the present invention is to provide such a mechanism,which may be used with many different types of transmissions.

Another object of the present invention is to provide such a mechanism,which is both efficient and reliable and requires no external control.

The torsion damping mechanism of the present invention is adapted forinstallation in a driveline, having an input drive and an output driverespectively driven by an engine and driving a load. The torsion dampingmechanism is disposed between the drives and includes a torsional energyisolating spring(s) and a torsional energy damping device disposed inparallel with the spring; the spring is connected at its opposite endsto the drives and allows limited relative rotation between the drives.

According to a feature of the invention, the torsion damping mechanismincludes first and second members mounted for relative rotation about acommon axis for clutching coaction therebetween to damp drivelinetorsionals, and spring(s) interconnecting the members in parallel withthe clutching coaction for transmitting steady-state driveline torquebetween the input and output drives and for isolating drivelinetorsionals. The improvement comprises clutching surfaces defined by themembers and retained against axial and radial movement relative to eachother; the surfaces are operative to effect the clutching coactionbetween the members, and the surfaces are shaped to vary the amount ofclutching coaction for varying the amount of damping of the drivelinetorsionals in response to the level of steady-state driveline torquebeing transmitted by the spring(s).

According to another feature of the present invention, the first memberforms part of an annular housing assembly defining an annular chambercontaining a viscous shear liquid, the second member forms part of anannular clutch assembly disposed within the chamber, and the surfacesare operative to vary the amount of viscous clutching coaction andaccordingly the amount of damping of the driveline torsionals inresponse to the relative rotational positions of the surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

The torsion damping mechanism of the present invention is shown in theaccompanying drawings in which:

FIG. 1 is a schematic view of a portion of a motor vehicle driveline,including the torsion damping mechanism of the present invention;

FIG. 2 is a chart showing clutch and brake engagement for shifting thetransmission of FIG. 1;

FIG. 3 is a partial, detailed, sectional view of a transmission shown inFIG. 1 with the torsion damping mechanism also shown in detail;

FIG. 4 is an elevational view of the torsion damping mechanism lookingalong line 4--4 of FIG. 3;

FIGS. 5 and 6 are of viscous clutching members in the mechanism of inFIG. 4 looking in the direction of arrow 5; and

FIG. 7 is a graph schematically illustrating the clutching coaction ordamping factor, G, of the members in FIGS. 5 and 6 as a function oftheir relative positions.

DETAILED DESCRIPTION

The motor vehicle driveline, seen schematically in FIG. 1, includes aninternal combustion engine 10 and an automatic transmission 12 having anoutput drive or gear 14 for driving a load, such as unshown rear and/orfront wheels of a vehicle.

The transmission 12 comprises a hydrokinetic fluid coupling or torqueconverter 16, a ratio section 18, and a torsion damping mechanism 19including a spring assembly 20 and a viscous coupling assembly 22.Components 16-22 are substantially symmetrical about a rotational axisdefined by a shaft 21 of the transmission and are shown only above theaxis for simplicity and brevity.

Torque converter 16 is disposed within a torque converter housing 24rotationally driven by an input drive 26 connected directly to an outputor crankshaft 28 of the engine. Converter 16 may be of any well-knowntype and includes an impeller 30 driven by housing 24, a turbine 32driven hydrokinetically by the impeller, and a stator 34 connectable bya one-way roller clutch 36 to a ground such as a nonrotatable portion ofthe unshown transmission housing.

Transmission 12 is a modified form of the general known class of splitinput torque transmissions disclosed in U.S. Pat. No. 4,398,436 andBritish patent application No. 2,099,091A, both of which areincorporated herein by reference. Ratio section 18 comprises a planetarygear set 38 controlled by friction clutches C-1, C-2, one-way clutchOWC-1 and brakes B-1, B-2 to provide a reverse and three forward speedratio modes of operation. Planetary gear set 38 includes a first sungear 40, first and second sets of planetary gears 42, 44 supported by acommon planet carrier 46, a ring gear 48, and a second sun gear 50. Sungear 40 is connectable to a first quill or torque converter driven shaft52 via clutch C-1 or clutch OWC-1. The first and second sets ofplanetary gears are in constant mesh with each other, with sun gear 40,and with ring gear 48, respectively. Planet carrier 46 is in constant ordirect driving relation with output gear 14. Ring gear 48 is connectableto ground via brake B-1 or to a second quill shaft 54 via clutch C-2.Shafts 21, 54 are fixedly interconnected at 56, and shaft 54 isconnected to clutch C-2 via a radially extending flange 58. Sun gear 50is in constant mesh with planetary gears 42 and is connectable to groundvia brake B-2. Ratio section 18 further includes an oil pump 60 drivenby shaft 21.

Looking now specifically at torsion damping mechanism 19, springassembly 20 includes two flat torsion springs 61, 62, more clearly seenin FIG. 4; the viscous coupling assembly 22 includes an annular housingassembly 64 and an annular clutch assembly 66. Housing assembly 64includes an annular radially extending sidewall member 24a defined bythe left wall of torque converter housing 24 and an annular radiallyextending wall member 68 fixed at its radially outer periphery tohousing 24. Walls 24a, 68 define an annular chamber 70 containing aviscous liquid. Annular clutch assembly 66 includes an annular clutchmember 72 disposed for limited rotation in the chamber relative to thehousing and fixed to a hub assembly 74. The hub assembly is, in turn,fixed to transmission shafts 21, 54, at 56 and to the inner race of aone-way clutch OWC-2 having its outer race fixed to turbine 32. Springs61, 62 are fixed at their radially outer ends 61a, 62a to housing 24 andat their radially inner ends 61b, 62b to hub assembly 74 in FIG. 1. Hubassembly 74 is clutchable to turbine 32 and quill shaft 52 via one-wayclutch OWC-2. Clutches OWC-1 and OWC-2 are preferably of the rollertype. Only spring ends 61a and 62b are visable in FIG. 1. Springs 61, 62resiliently connect torque converter housing 24 directly to transmissionshafts 21, 54. The springs also resiliently interconnect couplingassemblies 64, 66 for allowing relative rotational positioning of theassemblies in response to variations in the steady-state drivelinetorque being transmitted by the springs, and for allowing relativeto-and-fro rotation of the assemblies about the steady-state positionsof the assemblies in response to driveline torsionals and in response toabrupt changes in driveline torque.

Operation of transmission 12 is in accordance with the FIG. 2 chart,showing clutch and brake engagements to effect the reverse and forwardspeed ratio modes of operation. In first and reverse, 100% of drivelinetorque is transmitted to the ratio section via the torque converter(T/C). In second and third, 100% of the driveline torque is transmittedvia torsion spring assembly (T/S) 20. When the transmission is in third,clutch OWC-2 engages to provide a torque reaction for sun gear 40. Whilethe transmission is in either second or third, driveline torsionalsemanating from the engine are isolated by torsion spring assembly 20 andare dampened by the viscous clutching coaction between members 24a, 68,72 of the viscous coupling. The damping occurs independent of thesteady-state torque in the driveline and independent of the magnitude ofthe torsionals, since the viscous clutching coaction between members24a, 68, 72 of the viscous coupling is always proportional to themagnitude of the torsionals. That is, since the members are viscouslyinterconnected, the members will always slip and dampen pulses ortorsionals capable of deflecting the torsion springs of spring assembly20.

The function of torsion damping mechanism 19, as thus far explained, issubstantially the same as the torsion damping mechanism disclosed in thepreviously mentioned copending patent application Ser. No. 564,537. Theviscous coupling in the mechanism of the copending application providesa constant damping factor (viscous clutching coaction) and providesexcellent results over the entire driveline torque range of testedvehicles. These results may be further improved by varying the dampingfactor of the viscous coupling. FIGS. 3-6 herein illustrate a viscouscoupling having a variable damping factor as a function of drivelinetorque.

Mechanism 19 of this application may employ a torsion shaft or helicalcoil springs such as disclosed in the copending application in lieu ofthe flat torsion springs disclosed herein. Further, viscous coupling 22herein may employ concentric interdigitally arranged rings definingviscous clutching surfaces such as disclosed in the copendingapplication in lieu of the flat viscous clutching surfaces disclosedherein.

Looking now at the detailed embodiment of FIGS. 3-6, this embodimentincludes means providing the viscous coupling with the variable dampingfactor feature. The coupling is otherwise substantially the same asschematically illustrated in FIG. 1. In addition to the variable dampingfactor feature, coupling 22 includes several other advantageousfeatures: (1) the left sidewall 24a of the coupling housing assembly 64is defined by the torque converter housing, thereby (a) negating thecost of one sidewall, (b) reducing the thickness of the coupling which,at best, is difficult to fit into the available space within the torqueconverter housing, and (c) negating the need for a second dynamic sealto prevent fluid leakage into and out of the coupling; (2) the flatplate structure of the viscous clutching surfaces further reduces thecoupling thickness and additionally reduces the coupling cost since thehousing and clutching members 24a, 68, 72 may be formed of stampingsrequiring little or no machining; and (3) the reduced thickness providedby features (1) and (2) provides space in the torque converter housingfor spring assembly 20.

The annular housing assembly 64 is composed of the sidewall members 24a,68 spaced apart by an annular ring 76 to define chamber 70 and toestablish the axial distance between inner surfaces 24b, 68a of themembers. Surfaces 24b, 68a are substantally parallel and cooperate withclutch member 72 to define the viscous clutching or working portion ofthe coupling. Ring 76 is secured to housing 24 by an unshown weld andsidewall member 68 is secured to ring 76 by a plurality ofcircumferentially spaced screws 78. The outer periphery of chamber 70 issealed by the weld and a static seal 80. The radially outer portion ofsidewall member 68 includes a cylindrical flange 68b having spring ends61a and 62a secured thereto by screws 82, as may be seen in FIG. 4. Theradially inner portion of member 68 includes a cylindrical flange 68cextending axially to the left and defining a bearing surface on itsinner surface.

Hub assembly 74 of clutch assembly 66 includes a hub member 84 and anannular radially extending flange member 86 secured to the inner race ofclutch OWC-2 by a plurality of circumferentially spaced screws 88. Tworadially extending slots in the radially outer portion of flange 86receive tangs or ends 61b, 62b of springs 61, 62, as fully shown in FIG.4. Hub member 84 includes a radially inner hub portion 84a, an annularintermediate hub portion 84b, and a cylindrical outer flange 84c. Hubportion 84a includes a blind hexagonal opening mating with a hexagonalportion 21a at the left end of shaft 21. The right end of shaft 21includes a hexagonal portion 21b received in a mating hexagonal openingin a bracket 60a. The bracket drives oil pump 60, shown schematicallyonly in FIG. 1. The inner surface of hub portion 84b includes a portion84d receiving a smooth outer surface on the left end of quill shaft 54and a splined portion 84e mating with splines 54a on the outer surfaceof the quill shaft. Flow of pressurized transmission fluid along theinterface of hub portion 84b and quill shaft 54 is prevented by a staticseal 90. A bearing sleeve 92, pressed on the outer surface of hubportion 84b, provides a journal for the bearing surface defined bycylindrical flange 68c of sidewall member 68. Fluid leakage into and outof chamber 70 at the hub is prevented by a single dynamic seal 94 of thedouble lip elastomer-type pressed at its outer periphery on the innerperiphery of cylindrical flange 84c and running on its inner peripheryagainst a sleeve 96 pressed on the outer periphery of cylindrical flange68c of sidewall member 68. A snap ring 98 prevents axial movement of theseal. Transmission fluid leakage along the journal surface of bearing 92is directed to an oil return via one or more radially inwardly extendingholes 99. Metal-to-metal contact between housing wall 24a and hub member84 is prevented by an annular thrust bearing 100. The outer periphery ofhub member 84 or flange portion 84c includes a plurality ofcircumferentially spaced teeth or splines 84f.

Clutch member 72 is substantially annular and includes an innerperiphery having a plurality of circumferentially spaced splines 72amating with splines 84f of hub member 84, an intermediate or workingportion having oppositely facing surfaces 72b, 72c, and a radially outerportion 72d. Outer portion 72d includes a plurality of circumferentiallyspaced throughholes each receiving from opposite sides a roundantifriction material 102 of T-shaped cross section for centering clutchmember 72 in chamber 70.

Looking now at sidewall surfaces 24b, 68a and clutch member surfaces72b, 72c, as may be seen in FIGS. 3, 5, and 6, surface 24b includesarcuate recesses 24c, 24d each of about 100 arc degrees in length anddefining therebetween arcuate clutching surfaces 24e, 24f each of about80 arc degrees in length. Clutching surfaces 24e, 24f are fully visiblein FIG. 5 and partly visible in FIG. 6. The leading/trailing edges ofrecess 24c, 24d are designated 24g, 24h, 24i, 24j. These edges alsodefine the leading/trailing edges of clutching surfaces 24e, 24f. Sur68a of sidewall member 68 includes identical arcuate recesses disposeddirectly opposite recesses 24c, 24d and arcuate clutching surfacesdisposed directly opposite clutch surfaces 24e, 24f. The recesses andclutching surfaces of sidewall surface 68a are not shown in FIGS. 5 and6; one recess designated 68d is visible in FIG. 3. The oppositely facingrecesses and arcuate clutching surfaces in sidewall surfaces 24b, 68aprovide chamber 70 with axial widths which change stepwise from amaximum to a minimum. Herein the recesses are machined into thesidewalls. However, the recesses may be formed in other ways, e.g., therecesses may be made by deforming the sidewalls outward. Surfaces 72b,72c also include arcuate recesses or throughopenings 72f, 72g of about100 arc degrees in length and defining therebetween, on the oppositelyfacing surfaces 72b, 72c of the clutch member 72, arcuate clutchingsurfaces of about 80 arc degrees in length. The arcuate clutchingsurfaces on surface 72b are not shown in the drawing. The arcuateclutching surfaces on surface 72c are designated 72h, 72i, and both arefully visible in FIGS. 5 and 6. The leading/trailing edges ofthroughopenings 72f, 72g are designated 72j, 72k, 72m, and 72n. Theseedges also define the leading/trailing edges of the clutching surfaceson the oppositely facing surfaces 72b, 72c.

With a point A on clutch member 72 in FIGS. 5 and 6 taken as a zerodegree reference position and with all degree positions taken in aclockwise direction, FIG. 5 depicts recess 24c extending between the270° and 10° positions, recess 24d extending between the 90° and 190°positions, throughopening 72f extending between the 355° and 95°positions, and throughopening 72g extending between the 175° and 275°positions. In FIG. 6, the rotational position of clutch member 72 isunchanged and housing assembly 64 is rotated 80 arc degrees clockwise.If housing assembly 64 were rotated an additional 5 arc degrees, each ofthe recesses/throughopenings would be completely disposed opposite eachother and likewise each of the arcuate clutching surfaces would becompletely disposed opposite each other.

The recess/throughopening and arcuate clutching surface arrangementprovides viscous coupling 22 with a clutching or damping factor whichvaries in response to variations in the relative rotational positions ofthe arcuate clutch surfaces. When the arcuate clutching surfaces of thesidewall members and the clutch member are all disposed oppositerecesses or throughopening, as shown in FIG. 5, the damping factor ofthe coupling is a minimum. When the arcuate clutching surfaces overlieeach other, as substantially shown in FIG. 6, the damping factor of thecoupling is a maximum.

Since housing assembly 64 and clutch assembly are resilientlyinterconnected by spring assembly 20, the relative rotational positionof the arcuate clutching surfaces is controlled by the level ofsteady-state driveline torque being transmitted by the spring assembly.For example, torsion damping mechanism 19 may be assembled such that thearcuate clutching surfaces are as shown in FIG. 5 when a land vehiclehaving transmission 12 disposed therein is stopped with the transmissionin gear and the engine at the idle throttle position. Under suchconditions, the damping factor of the coupling, as shown in the graph ofFIG. 7, is at a minimum and varies along curve G in response todriveline torsionals. As steady-state driveline torque is increased inresponse to higher power demands by the throttle, spring assembly 20yields and establishes a new position on curve G about which the dampingfactor varies in response to driveline torsionals. For example, in theidle throttle position of FIG. 5, the damping factor is constant fortorsionals which cause relative rotations between -5° and +15°. Thedamping factor increases for relative rotations greater than the -5° and+15°. As the steady-state torque increases, new relative rotationalpositions of the arcuate clutching surfaces are established. Forexample, a 60° relative rotation effected by a steady-state torque,establishes damping factors which vary about a point B on curve G.Spring assembly 20 may be sized such that, under normal operatingconditions, 90° of relative rotation occurs. Stops for limiting theamount of relative rotation of housing assembly 64 relative clutchassembly 66 may also be used or in the alternative, greater amounts ofrelative rotation may be allowed, in which case the damping factor ofthe disclosed arrangement would then decrease from a peak along a pathor curve defined by phantom line G'.

While a preferred embodiment of the present invention has beenillustrated and described in detail, it will be apparent that variouschanges and modifications may be made in the disclosed embodimentwithout departing from the scope or spirit of the invention. Forexample, the leading/trailing edges of the recesses and/or thethroughopenings in the sidewalls and clutch member may be curved orslanted relative to each other to provide other than the linear dampingfactor curve of FIG. 7. The viscous coupling housing assembly may bemade in a more conventional manner wherein sidewall 24a is not part ofthe torque converter housing. The torsion damping mechanism may also beused to damp torsionals of many different types of drivelines. Theabrupt stepwise shape of the leading/trailing edges of therecesses/throughopening may be tapered. Still further, the sidewalls andclutching member may each have any number of arcuate clutching surfaces,e.g., each may have one arcuate clutching surface of about 180 arcdegrees or more than the two arcuate clutching surfaces disclosedherein. The appended claims are intended to cover these and othermodifications believed to be within the spirit of the invention.

What is claimed is:
 1. A torsion damping mechanism adapted for torquetransmitting connection between an engine driven drive of vehicledriveline and a transmission drive; the mechanism comprising a damperassembly and a resilient assembly; the damper assembly including firstand second means mounted for relative rotation about a common axis forclutching coaction therebetween to dampen driveline torsionals; theresilient assembly interconnecting the first and second means inparallel with the clutching coaction for transmitting steady-statedriveline torque between the drives and for isolating drivelinetorsionals; the improvement comprising:said damper assembly being aviscous damper including annular housing and clutch assembliesrespectively defining said first and second means, said housing assemblyincluding first and second radially extending sidewall members adaptedto be drivingly connected at a radially outer extent to the enginedriven drive, said sidewall members having mutually facing sidewallsurfaces defining an annular radially extending chamber closed at itsradially outer extent by means sealingly securing the sidewall memberstogether, said clutch assembly including radially outer and innerportions, and said outer portion having oppositely facing radiallyextending clutch surfaces disposed in axially spaced relation from theirassociated sidewall surfaces for viscous clutching coaction therebetweenvia a viscous liquid in the chamber; and said resilient assemblyincluding a hub member and at least two spiral wound springs, said hubmember being drivingly connected to said clutch inner portion andadapted for positive driving connection with the transmission drive, andsaid spiral springs each having a radially outer end and a radiallyinner end respectively and symmetrically attached for positive drivewith said housing assembly and said hub member.
 2. The mechanism ofclaim 1, wherein said clutch inner portions and hub member includemating splines providing the positive driving connection therebetween.3. The mechanism of claim 1, wherein said transmission includes a torqueconverter disposed with a toruqe converter housing and said mechanism isadapted to be disposed within the torque converter housing.
 4. Themechanism of claim 3, wherein the torque converter includes a radiallyextending wall portion defining one of the sidewalls of said annularhousing assembly.
 5. The mechanism of claim 1, wherein said sidewallmembers and said clutch outer portion are retained against axial andradial movement relative to each other, and said associated sidewall andclutch surfaces are shaped to vary the clutching coaction therebetweenand accordingly the amount of damping of driveline torsionals inresponse to the relative rotational positions of said associatedsurfaces.